1、 Standard Test Method Testing of Embeddable Impressed Current Anodes for Use in Cathodic Protection of Atmospherically Exposed Steel-Reinforced Concrete This NACE International standard represents a consensus of those individual members who have reviewed this document, its scope, and provisions. Its
2、 acceptance does not in any respect preclude anyone, whether he or she has adopted the standard or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not in conformance with this standard. Nothing contained in this NACE International standard is to be constru
3、ed as granting any right, by implication or otherwise, to manufacture, sell, or use in connection with any method, apparatus, or product covered by Letters Patent, or as indemnifying or protecting anyone against liability for infringement of Letters Patent. This standard represents minimum requireme
4、nts and should in no way be interpreted as a restriction on the use of better procedures or materials. Neither is this standard intended to apply in all cases relating to the subject. Unpredictable circumstances may negate the usefulness of this standard in specific instances. NACE International ass
5、umes no responsibility for the interpretation or use of this standard by other parties and accepts responsibility for only those official NACE International interpretations issued by NACE International in accordance with its governing procedures and policies, which preclude the issuance of interpret
6、ations by individual volunteers. Users of this NACE International standard are responsible for reviewing appropriate health, safety, environmental, and regulatory documents and for determining their applicability in relation to this standard prior to its use. This NACE International standard may not
7、 necessarily address all potential health and safety problems or environmental hazards associated with the use of materials, equipment, and/or operations detailed or referred to within this standard. Users of this NACE International standard are also responsible for establishing appropriate health,
8、safety, and environmental protection practices, in consultation with appropriate regulatory authorities if necessary, to achieve compliance with any existing applicable regulatory requirements prior to the use of this standard. CAUTIONARY NOTICE: NACE International standards are subject to periodic
9、review, and may be revised or withdrawn at any time in accordance with NACE technical committee procedures. NACE International requires that action be taken to reaffirm, revise, or withdraw this standard no later than five years from the date of initial publication. The user is cautioned to obtain t
10、he latest edition. Purchasers of NACE International standards may receive current information on all standards and other NACE International publications by contacting the NACE International FirstService Department, 1440 South Creek Dr., Houston, TX 77084-4906 (telephone +1281228-6200). Revised 2007-
11、06-22 Reaffirmed 2001-09-05 Approved March 1994 NACE International 1440 South Creek Drive Houston, Texas 77084-4906 +1 281/228-6200 ISBN 1-57590-133-1 2007, NACE International NACE Standard TM0294-2007 Item No. 21225 TM0294-2007 NACE International i _ Foreword This NACE International standard has be
12、en prepared to provide users and manufacturers of embeddable anodes with a test method for evaluating the anode material to an expected lifetime criterion. It is applicable to embeddable anode materials, such as titanium mesh, commonly used for cathodic protection of atmospherically exposed steel-re
13、inforced concrete. The test method is intended to evaluate whether an embeddable anode material complies with minimum required specifications of design life expectancy at rated current output. This test method is not applicable to surface-mounted anodes or conductive coating materials. This NACE Int
14、ernational test method was originally prepared in 1994 by Task Group (TG) T-3K-6 on Test Procedure for Anodes Used in Concrete, a component of Unit Committee T-3K on Corrosion and Other Deterioration Phenomena Associated with Concrete. It was reviewed by TG 045 on Anodes Test Procedures and reaffirm
15、ed in 2001 by Specific Technology Group (STG) 01 on Concrete and Rebar. It was revised by TG 045 in 2007. TG 045 is administered by STG 01 and sponsored by STG 05 on Cathodic/Anodic Protection. This standard is issued by NACE International under the auspices of STG 01, now called Reinforced Concrete
16、. In NACE standards, the terms shall, must, should, and may are used in accordance with the definitions of these terms in the NACE Publications Style Manual, 4th ed., Paragraph 7.4.1.9. Shall and must are used to state mandatory requirements. The term should is used to state something good and is re
17、commended but is not mandatory. The term may is used to state something considered optional. _ TM0294-2007 ii NACE International _ NACE International Standard Test Method Testing of Embeddable Impressed Current Anodes for Use in Cathodic Protection of Atmospherically Exposed Steel-Reinforced Concret
18、e Contents 1. General 1 2. Definitions . 2 3. Solution Preparation. 2 4. Test Apparatus. 3 5. Test Procedure 5 6. Anode Failure. 5 7. Reporting Test Results 5 References 5 FIGURES Figure 1: Test Cell with Luggin Probe Anode Potential Measurement Setup 3 Figure 2: Series Electrical Hookup for Duplica
19、te Evaluations 4 _ TM0294-2007 NACE International 1 _ Section 1: General 1.1 Accelerated testing of anodes for use in concrete is intended to provide an indication of an anodes ability to perform satisfactorily for a specific number of years. Unfortunately, accelerated life testing cannot be conduct
20、ed in concrete because testing at high current levels results in premature failure of the concrete as the test electrolyte. Accelerated life testing must therefore be conducted in an aqueous solution. 1.1.1 When using accelerated life tests, anodes shall be demonstrated to survive a minimum total ch
21、arge density of 38,500 A-h/m2(3,580 A-h/ft2) of actual anode surface area. This is the amount of total charge density an anode is subjected to if operated at a current density of 108 mA/m2(10 mA/ft2) of anode surface for 40 years. If an anode is designed to operate at any other current density, the
22、test should be modified to reflect the charge density equivalent to 40 years of operating life. 1.1.2 Under certain circumstances, the user may require a greater total charge density than 38,500 A-h/m2(3,580 A-h/ft2) of anode surface, because of a longer life requirement than 40 years, or because of
23、 a higher operating current density. In these cases, the test may be extended or the charge density increased until the desired charge is met. 1.2 It is possible that a cathodic protection (CP) anode may be incorrectly powered cathodically during the initial system energization. This condition may n
24、ot be noticed by merely observing the rectifier meters and can remain undetected until the depolarization test is performed after several days of operation. It is also possible that an anode may be exposed to current reversal caused by an electrical short between the anode and the steel. In this cas
25、e, the anode is subjected to cathodic current until the system is energized and tested, sometimes several months later. In view of these possibilities and the serious implications of damage to the anode, the ability of the anode to survive a brief current reversal must be ensured. 1.2.1 Assuming the
26、 anode is operated at a reversed current density of 108 mA/m2(10 mA/ft2) of anode surface for one month, the anode experiences approximately 71 A-h/m2(6.6 A-h/ft2) of cathodic charge density. It shall be tested to endure such a current reversal and then continue to provide an equivalent of at least
27、40 years, or 38,500 A-h/m2(3,580 A-h/ft2) of anode surface, of protection. 1.3 The anodic portion of life testing shall be conducted over a period of at least 180 days. 1.4 Life testing shall be conducted using a constant current, filtered direct current (DC) power supply having a maximum ripple of
28、5%. 1.5 Accelerated life testing shall be conducted in duplicate in the following aqueous solutions: 1.5.1 30 g/L of sodium chloride in distilled or deionized water 1.5.1.1 Cathodic protection anodes are often used to protect bridge piers and pilings in seawater and therefore are exposed to this chl
29、oride environment. This solution tests the ability of anodes to tolerate the chlorine evolution reaction. 1.5.2 40 g/L of sodium hydroxide in distilled or deionized water 1.5.2.1 This solution, though at a higher pH than concrete, is conductive enough to nullify effects of solution changes. The solu
30、tion also tests the ability of the anode to tolerate oxygen evolution, a reaction more favored at low current density and the low chloride contamination level experienced with fresh overlays. 1.5.3 Simulated pore water in sand 1.5.3.1 The electrolyte available to the anode in a cured concrete struct
31、ure is pore water. This solution tests the ability of the anode to tolerate the actual concentrations of the pore water components and any possible synergistic effects imposed by these components. The use of fine sand to encompass the electrode, eliminating convective mixing, tests the ability of th
32、e anode to tolerate the situation most closely simulating its operation in cured concrete. The composition by mass of simulated pore water used shall be as follows: 0.20% Ca(OH)23.20% KCl 1.00% KOH 2.45% NaOH 93.15% distilled or deionized water 1.6 Failure of the anode shall be determined by loss of
33、 the electrochemical activity as evidenced by an increase in anode potential as discussed in Paragraph 6.2. TM0294-2007 2 NACE International _ Section 2: Definitions Luggin Probe: A small tube or capillary filled with electrolyte, terminating close to the metal surface of an electrode under study, w
34、hich is used to provide an ion-conducting path without diffusion between the electrode under study and a reference electrode. Ripple: The alternating current (AC) component in the output of a DC power supply, arising within the power supply from incomplete filtering or from commutator action in a DC
35、 generator. _ Section 3: Solution Preparation 3.1 30 g/L Sodium Chloride (NaCl) Solution 3.1.1 30.0 g of reagent grade NaCl shall be weighed and added to a 1.0-L volumetric flask. 3.1.2 Approximately 500 mL of distilled or deionized water shall be added to the above, and the solution must be swirled
36、 in the flask until the NaCl crystals are totally dissolved. 3.1.3 The volumetric flask shall be filled to the 1.0-L mark with distilled or deionized water, and the solution must be thoroughly mixed. 3.2 40 g/L Sodium Hydroxide (NaOH) Solution 3.2.1 40.0 g of solid NaOH pellets shall be weighed as r
37、eagent grade NaOH and slowly added to a 1.0-L volumetric flask containing approximately 500 mL of distilled or deionized water. The solution must be swirled in the flask until the NaOH is totally dissolved. This reaction is exothermic and generates heat. 3.2.2 The volumetric flask shall be filled to
38、 just under the 1.0-L mark with distilled or deionized water and the solution shall be allowed to cool to room temperature. 3.2.3 When the solution is cool, the volumetric flask shall be filled to the 1.0-L mark with distilled or deionized water, and the solution shall be thoroughly mixed. 3.3 Simul
39、ated Pore Water in Sand 3.3.1 26.3 g of solid NaOH pellets shall be weighed out as reagent grade NaOH and slowly added to 1.0 L of distilled or deionized water in a flask. This reaction is exothermic and generates heat. 3.3.2 10.74 g of solid potassium hydroxide (KOH) pellets shall be weighed out as
40、 reagent grade KOH and slowly added to the solution. The solution must be swirled until all pellets are dissolved. 3.3.3 34.35 g of reagent grade potassium chloride (KCl) shall be weighed out and added to the solution. The solution shall be swirled until the crystals are dissolved. 3.3.4 2.15 g of r
41、eagent grade calcium hydroxide (CaOH2) shall be weighed out and added to the solution. The solution shall be mixed with a magnetic stirrer until it has cooled. 3.3.5 Fine natural silica sand (40 to 50 mesh) shall be obtained in accordance with ASTM(1)C 778.13.3.6 The test cell must first be filled w
42、ith enough sand to cover the anode completely after the electrodes and Luggin probe are in place. The simulated pore water shall then be added to displace any air and fill the remainder of the cell. 3.3.7 Fresh sand and solution shall be used for the current reversal test (Paragraph 5.5) and for the
43、 normal current test (Paragraph 5.9). _ (1)ASTM International (ASTM), 100 Barr Harbor Dr., West Conshohocken, PA 19428. TM0294-2007 NACE International 3 _ Section 4: Test Apparatus 4.1 Test Cell 4.1.1 The test cell shall be a tall-form glass 1.0-L beaker that is 183 mm (7.1 in.) high and 91 mm (3.6
44、in.) in diameter, fitted with a No. 15 rubber stopper at the top to hold the electrodes and reduce air contact. Glass beakers of other sizes may be used as long as electrodes remain immersed for the duration of the test. The gap between the anode and cathode shall be approximately 50 mm (2 in.). The
45、 rubber stopper shall have a hole located midway between the electrodes that is fitted with an extension tube to vent gases away from the electrical connections. This hole may be used to locate the current reverse supplemental anode and Luggin probe. There shall be an additional hole large enough to
46、 measure pH of the test solution. Figure 1 shows a typical setup for a test cell with Luggin probe for anode potential measurement. FIGURE 1 Test Cell with Luggin Probe Anode Potential Measurement Setup 4.1.2 A sample of the anode having 2000 mm2(3.1 in.2) of anode surface area shall be used. The an
47、ode surface area shall be calculated by including all the surfaces that will be in contact with concrete when embedded. A titanium anode sample shall be welded to a 1.6-mm diameter x 203-mm long (0.063-in. diameter x 8-in. long) titanium rod in two spots as shown in Figure 1. The titanium rod acts a
48、s the current carrier. For other types of anodes, an appropriate anode connection as recommended by the anode manufacturer shall be made. The anode shall be connected to the positive lead of the power supply (the TM0294-2007 4 NACE International negative lead during the current reversal test) extern
